The standard defines various file streams in the header file fstream. These streams do not accept parameters of type boost::filesystem::path. If you want to open file streams with objects of type boost::filesystem::path, include the header file boost/filesystem/fstream.hpp.
boost::filesystem::ofstream#include <boost/filesystem/fstream.hpp>
#include <iostream>
using namespace boost::filesystem;
int main()
{
path p{"test.txt"};
ofstream ofs{p};
ofs << "Hello, world!\n";
}Example 35.19 opens a file with the help of the class boost::filesystem::ofstream. An object of type boost::filesystem::path can be passed to the constructor of boost::filesystem::ofstream. The member function open() also accepts a parameter of type boost::filesystem::path.